U.S. patent number 5,833,001 [Application Number 08/768,027] was granted by the patent office on 1998-11-10 for sealing well casings.
This patent grant is currently assigned to Schlumberger Technology Corporation. Invention is credited to Jack F. Lands, Jr., Haoshi Song, Wallace E. Voreck.
United States Patent |
5,833,001 |
Song , et al. |
November 10, 1998 |
Sealing well casings
Abstract
An apparatus and method for sealing an inner wall of a portion
of a casing positioned in a well employs an inflatable sleeve
having an outer surface and a conformable composite sleeve of
curable composition extending around the outer surface of the
inflatable sleeve. The inflatable sleeve is inflated to compress
the composite sleeve against the surface of the inner casing wall.
A local, activatable energy source, positioned downhole to deliver
heat to the composite sleeve, is activated to cure the composite
sleeve to form a hardened sleeve. The hardened sleeve presses
against the inner wall of the casing portion to create a fluid
seal. The embodiments shown have a number of preferred features.
The local energy source includes an exothermic heat energy source
for generating heat energy to cure the composite sleeve. The
composite sleeve includes a mixture of resin and a curing agent,
and the exothermic heat source includes thermite. The thermite
includes a composition having a metal oxide and a reductant. A
starter mix is positioned adjacent the exothermic heat energy
source, and the starter mix is ignited to start an exothermic
reaction in the heat energy source. A conformable layer extends
around the composite sleeve, with the layer serving to form a seal
between the composite sleeve and the inner wall of the casing
portion.
Inventors: |
Song; Haoshi (Sugar Land,
TX), Lands, Jr.; Jack F. (West Columbia, TX), Voreck;
Wallace E. (Sparta, NJ) |
Assignee: |
Schlumberger Technology
Corporation (Sugar Land, TX)
|
Family
ID: |
25081311 |
Appl.
No.: |
08/768,027 |
Filed: |
December 13, 1996 |
Current U.S.
Class: |
166/287; 166/57;
166/207; 166/187; 166/277; 166/295; 166/300; 166/288 |
Current CPC
Class: |
E21B
43/105 (20130101); E21B 36/008 (20130101); E21B
33/1275 (20130101); E21B 29/10 (20130101); E21B
33/13 (20130101) |
Current International
Class: |
E21B
33/12 (20060101); E21B 33/13 (20060101); E21B
36/00 (20060101); E21B 29/10 (20060101); E21B
43/10 (20060101); E21B 29/00 (20060101); E21B
43/02 (20060101); E21B 33/127 (20060101); E21B
033/13 (); E21B 036/00 () |
Field of
Search: |
;166/57,187,206,207,277,287,288,295,300,302 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
AMCP 706-185 "Engineering Design Handbook, Military Pyrotechnics
Series Part One, Theory and Application" Headquarters, U.S. Army
Materiel Command, Apr. 1967, 7 total pages (excerpts), including
title page, pp. 5-6, 5-25, 5-40, 5-48, 5-49 and one unnumbered page
entitled: Engineering Design Handbooks. .
Linerflex In Situ Polymerisation Technology "Patch-Flex," pp. 1-4
(Sep. 1995). .
Drillflex Casing System, "Patch-Flex Characteristics and
Availability" pp.1-2 (Feb. 1996). .
J.L. Saltel et al., "In-situ Polymerisation of an Inflatable Sleeve
to Reline Damaged Tubing and Shut-off Perforations," Offshore
Technology Conference, pp. 1-9 (1996)..
|
Primary Examiner: Suchfield; George A.
Attorney, Agent or Firm: Waggett; Gordon G. Ryberg; John J.
Bouchard; John
Claims
What is claimed is:
1. Apparatus for sealing an inner wall of a portion of a casing
positioned in a well, comprising:
an inflatable sleeve having an outer surface;
a deformable composite sleeve of a curable composition extending
around the outer surface of the inflatable sleeve, wherein the
inflatable sleeve is inflatable to compress the composite sleeve
against the surface of the inner casing wall; and
a local activable heat source positioned downhole near the
composite sleeve, the heat source being activatable to generate
heat energy to cure the composite sleeve to form a hardened sleeve,
wherein the hardened sleeve presses against the inner wall of the
casing portion to create a fluid seal.
2. The apparatus of claim 1, wherein the local activable heat
source includes an exothermic heat energy source.
3. The apparatus of claim 1, wherein the composite sleeve includes
a mixture of resin and a curing agent.
4. The apparatus of claim 3, wherein the mixture is curable to a
hardened epoxy layer after exposure to the heat energy.
5. The apparatus of claim 1, wherein the local activable heat
source includes thermite.
6. The apparatus of claim 5, wherein the thermite includes a
composition having a metal oxide and a reductant.
7. The apparatus of claim 6, wherein the metal oxide is selected
from a group consisting of iron oxide and copper oxide.
8. The apparatus of claim 7, wherein the reductant is selected from
a group consisting of aluminum and silicon.
9. The apparatus of claim 1, further comprising:
a starter mix positioned adjacent the local activable heat source,
the starter mix being ignited to start an exothermic reaction in
the heat source.
10. The apparatus of claim 1, wherein the local activable heat
source is adapted to heat the composite sleeve to greater than
about 50.degree. C. above the ambient temperature of the well.
11. The apparatus of claim 1, further comprising:
a carrying tool for carrying the inflatable sleeve, the composite
sleeve, and the heat source down the well to the casing
portion.
12. The apparatus of claim 11, wherein the well includes a
production tubing having a first diameter, and wherein the carrying
tool has a second diameter less than the first diameter to allow
the carrying tool to be lowered down the production tubing.
13. The apparatus of claim 11, wherein the carrying tool further
includes means for inflating the inflatable sleeve, and wherein the
local heat source is an exothermic heat energy source mounted
centrally within the tool and means to inflate the inflatable
sleeve that enables heat transfer from the energy source to the
inflatable sleeve.
14. The apparatus of claim 1, further comprising:
a conformable layer extending around the composite sleeve, the
layer acting to form a seal between the composite sleeve and the
inner wall of the casing portion.
15. The apparatus of claim 1, further comprising a unitary downhole
tool including an assembly of the inflatable sleeve, the composite
sleeve and the local activatable heat source positioned to provide
curing heat to the composite sleeve.
16. A method of sealing an inner wall of a portion of a casing in a
well, comprising:
lowering an assembly of an inflatable sleeve, a composite, curable
sleeve, and an energy source down to the casing portion using a
carrying tool;
positioning the inflatable sleeve having an outer surface down the
well at the portion of the casing, and the composite, curable
sleeve extending around the outside of the inflatable sleeve;
inflating the inflatable sleeve to compress the composite sleeve
against the surface of the inner casing wall; and
activating a local energy source to cure the composite sleeve to
form a hardened sleeve, wherein the hardened sleeve presses against
the inner wall of the casing portion to create a fluid seal.
17. The method of claim 16, wherein the well includes a production
tubing, the method further comprising lowering the assembly through
the production tubing to the casing section.
18. The method of claim 16, wherein the local energy source
includes an exothermic heat energy source for generating heat
energy to cure the composite sleeve.
19. The method of claim 18, wherein the composite sleeve includes a
mixture of resin and a curing agent.
20. The method of claim 18, further comprising:
curing the mixture to a hardened layer after exposure to the
heat.
21. The method of claim 18, wherein the exothermic heat source
includes thermite.
22. The method of claim 18, further comprising:
igniting a starter mix positioned adjacent the exothermic heat
source to initiate an exothermic reaction in the heat source.
23. The method of claim 18, further comprising:
using the exothermic heat energy source to increase the temperature
to greater than 50.degree. C. above the ambient temperature of the
well.
24. The method of claim 16, wherein a conformable layer extends
around the composite sleeve, the layer acting to form a seal
between the composite sleeve and the inner wall of the casing
section.
25. The apparatus of claim 9, wherein the starter mix includes a
composition ignitable with a firing resistor.
26. The apparatus of claim 25, wherein the starter mix composition
includes a mixture of barium oxide and magnesium.
Description
BACKGROUND
The invention relates to sealing well casings.
After a well has been drilled and the casing has been cemented in
the well, one or more sections of the casing adjacent pay zones are
perforated to allow fluid from the surrounding formation to flow
into the well for production to the surface. Perforating guns are
lowered into the well and the guns are fired to create openings in
the casing and to extend perforations into the surrounding
formation. In the well shown in FIG. 1, two perforated regions 14
and 16 in the formation are shown next to two different sections of
the casing 12 in a well 10.
Contaminants (such as water or sand) are sometimes produced along
with the oil and gas from the surrounding formation. In the system
shown in FIG. 1, during production, fluid flows from the perforated
regions 14 and 16 through perforated openings in the casing 12 into
the bore 20 of the well 10. The fluid then rises up through a
production tubing 18 to the surface. A packer 22 positioned near
the bottom of the production tubing 18 is used to seal off well
fluids from the annulus 24 between the production tubing 18 and the
casing 12.
If contaminants are detected in the fluid from the production
tubing 18, then a logging tool is lowered into the well 10 to
determine the source of the contaminants. If, for example, the
source of contaminants is the perforated region 14, then the
perforated openings in the casing 12 are sealed to prevent fluid
flow from the perforated region.
To seal the desired section of the casing 12, one technique
typically used is referred to in the industry as a "squeeze job."
First, the production tubing 18 is removed from the well. Then, the
zone in the casing 12 adjacent the general area of the perforated
region 14 is isolated using temporary packers. Cement is pumped
down the bore 20 through a tube to the isolated zone to seal the
perforated openings in the desired section of the casing 12.
Drilling out of the cement is then required if production is
desired from a lower payzone.
Another technique has been proposed for sealing casing sections
downhole, which is described in J. L. Saltel et al., "In-Situ
Polymerization of an Inflatable Sleeve to Reline Damaged Tubing and
Shut-Off Perforations," Offshore Technology Conference, pp. 1-11
(May 1996). A cable carrying seven electrical conductors is used to
lower an inflatable sleeve which carries a permanent sleeve
(comprised of resins, fibers, and elastomers) downhole. The
inflatable sleeve is pressurized to push the permanent seal against
the inside surface of the casing. Electric power provided down the
wireline from the surface is used to generate heat to increase the
temperature of the resin for a sufficient period of time to cross
link (or "cure") the resin in the permanent sleeve. The permanent
sleeve is left downhole to maintain a seal over perforated sections
of the casing.
The electrical energy required to cross link the resin in the
system of Saltel et al. varies between 400 W/m and 1,900 W/m,
depending upon the diameters of the casing. To provide the
necessary electrical energy, a 1,250-volt DC supply is used at the
surface to generate about 2.5 amps of current through each of the
seven conductors and the associated resistive elements.
SUMMARY
In general, in one aspect, the invention features an apparatus for
sealing an inner wall of a portion of a casing positioned in a
well. The apparatus includes an inflatable sleeve having an outer
surface and a deformable composite sleeve of curable composition
extending around the outer surface of the inflatable sleeve, in
which the inflatable sleeve is inflated to compress the composite
sleeve against the surface of the inner casing wall. A local energy
source is positionable downhole near the composite sleeve, and the
energy source is activated to cure the composite sleeve to form a
hardened sleeve. (The term "local" is used here to exclude energy
sources that require substantial remote power generation and
conductors for that power.) The hardened sleeve presses against the
inner wall of the casing portion to create a fluid seal.
In general, in another aspect, the invention features a method of
sealing an inner wall of a portion of a casing positioned in a
well. An inflatable sleeve having an outer surface is lowered down
the well to the portion of the casing. A composite sleeve extends
around the outside of the inflatable sleeve. The inflatable sleeve
is inflated to compress the composite sleeve against the surface of
the inner casing wall. A local energy source is activated to cure
the composite sleeve to form a hardened sleeve. The hardened sleeve
presses against the inner wall of the casing portion to create a
fluid seal.
Implementations of the invention may include one or more of the
following features. The local energy source has an exothermic heat
energy source for generating heat energy to cure the composite
sleeve. The composite sleeve includes a mixture of resin and a
curing agent. The mixture is cured to a hardened epoxy layer after
exposure to the heat energy. The exothermic heat source includes
thermite. The thermite includes a composition having a metal oxide
and a reductant. The metal oxide is selected from a group
consisting of iron oxide and copper oxide. The reductant is
selected from a group consisting of aluminum and silicon. A starter
mix is positioned adjacent the exothermic heat source, and the
starter mix is ignited to start an exothermic reaction in a heat
energy source. The exothermic heat energy source heats the
temperature to greater than about 50.degree. C. above the ambient
temperature of the well. A carrying tool carries the inflatable
sleeve, the composite sleeve, and the energy source down the well
to the casing portion. The well includes a production tubing having
a first diameter, and the carrying tool has a second diameter less
than the first diameter to allow the carrying tool to be lowered
down the production tubing. A conformable layer of sheet or film
extends around the composite sleeve, and the layer acts to form a
seal between the composite sleeve and the inner wall of the casing
portion.
Advantages of the invention may include one or more of the
following. Production tubing can be left in place in the well while
a section of the casing is being sealed, which reduces
significantly production down time and the cost associated with the
casing perforation seal job. The energy source needed for the seal
job is local, downhole, which avoids the issues associated with
providing high energy from a surface source. As the energy source
is carried downhole with the sealing apparatus, and can be sized to
the length to be sealed, the effectiveness of the energy source is
not affected by the length of the seal or the depth of the well.
The inner diameter of the composite sleeve is large enough to allow
passage of tools for further operations below it in the well.
Other advantages and features will become apparent from the
following description and from the claims.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagram of a casing having perforated portions.
FIG. 2 is a diagram of a tool carrying a sealing sleeve down a
production tubing located in a casing.
FIGS. 3 and 4 are diagrams of the sealing sleeve being positioned
next to perforated openings in the casing and being inflated to
press the sealing sleeve against the inner wall of the casing.
FIG. 5 is a diagram of a permanent sleeve layer after it has been
cured and an inflatable sleeve layer which has been deflated after
the curing process.
FIGS. 6A and 6B are cross-sectional diagrams of the permanent
sleeve placed in the casing.
FIG. 7 is a diagram of multiple wells drilled through a formation
to illustrate how the sealing sleeve can be used to modify the
injection profile of a pay zone.
DESCRIPTION
To seal portions of the casing, a tool carrying a sealing sleeve
that includes an inner inflatable sleeve and an outer permanent
sleeve (containing an epoxy layer having a mixture of resin and a
curing agent, and a sealing film around the epoxy layer) is lowered
downhole to a desired section of the casing. Once properly
positioned downhole, the inflatable sleeve is inflated to compress
the permanent sleeve against the inner surface of the casing. The
permanent sleeve is then cured under compression to form a hardened
epoxy sleeve using a local source of heat energy lowered downhole
with the sealing sleeve by the carrying tool. The local source of
heat energy may be, by example, a thermite bar in which an
exothermic reaction is started to create a sufficient amount of
heat energy to cure the epoxy in the permanent sleeve. The
permanent sleeve, after the epoxy material has cured, stays fixed
to the inner surface of the casing section, and the inflatable
sleeve is deflated and detached from the permanent sleeve to allow
the tool to be pulled out. In this manner, a casing seal can be
created without the need for a high power electrical energy source
located at the surface and means to conduct that energy
downhole.
Referring to FIG. 2, a tool 32 carrying a sealing sleeve 31 is
lowered down a production tubing 18 into the bore 20 of the well
10. As shown in FIG. 2, and in greater detail in FIGS. 3 and 4, the
carrying tool 32 includes a tool head 34 attached to a wire line or
coiled tubing 30, which extends up to the surface. The tool head 34
is attached to the tool housing 48, which holds the sealing sleeve
31. The tool housing 48 includes an upper metal cap 39, a lower
metal cap 38, and a metal tube 49. The metal tube 49 is attached to
the upper and lower caps 39 and 38 with threads (not shown).
The sealing sleeve 31 is supported at the lower end of the tool 32
by the lower support metal cap 38 and at the upper end by the upper
support metal cap 39. A cylindrical thermite bar 36 is positioned
approximately along the center of the tool housing 48 inside the
metal tube 49, and enclosed on the top and bottom by the upper and
lower caps 39 and 38, respectively.
The sealing sleeve 31 includes a generally tubular, inflatable
bladder 44 (such as an elastic bladder formed e.g., of heat
resistant elastomer such as silicone rubber), which is shown in its
initial, deflated state in FIG. 2. A thin elastomer film or sheet
42 is stretched around the middle section of the bladder 44. An
epoxy layer 40 (which is a mixture initially in paste form of resin
and a curing agent) is inserted in the region between the bladder
44 and the film 42. The combination of the epoxy sleeve 40 and the
film 42 forms the permanent sleeve. Alternatively, a cyclindrical
layer of reinforcing materials, such as fibers or fabrics, could be
used with the epoxy layer 40 to increase the strength of the
permanent sleeve.
In one composition, the epoxy layer 40 is 100 parts resin and 28
parts curing agent (by weight). The resin is initially in liquid
form. The curing agent can be the Ancamine.TM. agent (which is
modified polyamine in powder form) from Air Products &
Chemicals, Inc. Once mixed, the resin and curing agent form a paste
material that can be pumped into the region between the bladder 44
and the film 42. The bladder 44 includes an epoxy fill port (not
shown) and a vacuum port (not shown). The region is first evacuated
through the vacuum port and then the epoxy layer is pumped into the
region between the bladder 44 and film 42 through the epoxy fill
port.
Different curing agents are available which cause the epoxy layer
to cure at different temperatures. Because of varying downhole
temperatures (which depend on such factors as the depth and
pressure of the well), the flexibility to choose different curing
temperatures is important. The range of minimum curing temperature
can be between 100.degree. C. and 130.degree. C.
Referring to FIG. 3, the carrying tool 32 is shown positioned next
to the portion of the casing 12 which is to be sealed using the
sealing sleeve 31. Once the sealing sleeve 31 is properly
positioned, a pump located in the tool head 34 is activated (from
the surface) to inflate the elastomer bladder 44 by pumping fluid
(e.g., water or surrounding well fluid) through line 60 (FIG. 4)
into the space 50 in the bladder 44. The inflation of the bladder
44 pushes the permanent sleeve (made up of the epoxy sleeve 40 and
the elastomer film 42) against the inner wall 52 of the casing 12.
The thermite bar 36 remains fixed in position by the metal tube 49,
the lower cap 38, and the upper cap 39.
Referring to FIG. 4, the section of the tool 32 carrying the
sealing sleeve 31 is shown in greater detail. The elastomer bladder
44 is shown in its inflated state pushing the permanent sleeve
against the inner wall 52 of the casing section containing
perforated openings 54. The elastomer bladder 44 is fitted between
an upper slot 58 in the upper support cap 39 and a lower slot 56 in
the lower support cap 38. The pump in the tool head 34 pumps fluid
into the space 50 in the bladder 44 through a fluid charge and
discharge line 60 to inflate the bladder.
If the system is used with a wireline, then commands to activate
the pump can be electrical signals. If, on the other hand, the
system is used with coiled tubing, pressure pulse signals can be
used, with a pressure pulse decoder located in the tool head to
sense the pressure pulse signals and to activate the pump if
appropriate signals are received.
A starter mix layer 64 overlays and is adjacent the top surface of
the thermite bar 36. A firing resistor 68 is positioned inside the
starter mix layer 64, and is connected by a wire 66 to an
electrical source (not shown) in the tool head 34. The electrical
source is switched on by an operator on the surface to fire the
firing resistor 68, which in turn fires the starter mix 68. The
electrical source can be activated by an electrical signal through
a wireline or pressure pulse signals if coiled tubing is used.
The starter mix 64 can be any composition which can be ignited with
the firing resistor 68, such as a composition having a mixture of
barium oxide (BaO.sub.2) and magnesium (Mg). After the starter mix
64 is ignited, a self-sustainable exothermic reaction is initiated
in the thermite 36, which releases a sufficient amount of heat
energy to cause the thermite mixture to react, melt, and become a
mixture of molten metal and reductant oxide. The exothermic
reaction is expressed by Eq. 1:
in which Me stands for a metal, R stands for a reductant, and O
stands for oxygen. This kind of thermite is a gasless mixture,
i.e., it does not generate gases during the exothermic reaction.
This avoids problems associated with pressure build up downhole if
gases are produced.
If the thermite mixture includes iron oxide and aluminum, the
exothermic reaction is expressed by Eq. 2.
The thermite 36 also can include other mixtures, including a
mixture of copper oxide (CuO or Cu.sub.2 O) and silicon (Si), or a
mixture of iron oxide (FeO, Fe.sub.2 O.sub.3, or Fe.sub.3 O.sub.4)
and silicon (Si). If the mixture contains copper oxide and silicon,
the exothermic reaction is expressed as Eq. 3.
If the mixture contains iron oxide and silicon, the exothermic
reaction is expressed as Eq. 4.
An upper insulation layer 70 is positioned between the starter mix
64 and the upper support cap 39, and a lower insulation layer 72 is
positioned between the thermite bar 36 and the lower support cap
38. In addition, an insulation layer 71 lies between the thermite
bar 36 and the metal tube 49. The insulation layers 70, 71, and 72
prevent the heat generated by the reacting thermite 36 from melting
the metal parts 39, 49, and 38, respectively. The insulation layers
can be made of a carbon/resin composite material.
The amount of heat generated by the exothermic reaction transfers
by radiation and convection to the outer layers and typically
elevates the temperature of the epoxy layer 40 to about 50.degree.
C. to 150.degree. C. above the ambient temperature of the well 10
for a few hours. Such elevated temperatures for this length of time
are sufficient to cure the resin and curing agent mixture in the
epoxy sleeve 40 to transform the paste mixture into a hardened
epoxy sleeve. Once the epoxy sleeve 40 is hardened, it remains
fixed against the inside surface 52 of the casing section, and the
elastomer film 42 acts as a seal to prevent fluid flow from the
formation through the perforated openings 54 of the casing.
Referring to FIG. 5, once the epoxy layer 40 in the permanent
sleeve has been cured, the pump in the tool head 34 discharges
fluid from the bladder 44 to deflate the bladder. The deflated
bladder 44 radially contracts and peels away from the epoxy sleeve
40. The carrying tool 32 can then be raised back through the
production tubing 18 by the wireline or coiled tubing 30.
Referring to FIGS. 6A-6B, cross-sectional views of the permanent
sleeve in place in the casing 12 show the epoxy sleeve 40, the
elastomer film 42, and the casing 12. FIG. 6A shows the
cross-sectional view of a casing having perforated holes 54.
Because it has been cured under compression, the hardened epoxy
sleeve 40 continues to press the elastomer film 42 against the
inner wall 52 of the casing 12 and seals the perforated openings
54, preventing fluid flow from the surrounding formation through
the perforated openings 54 to the casing bore 20. At the perforated
holes 54, as a result of the compressive forces during curing, the
elastomer film or sheet 42 partially extends into the holes 54,
conforming to the hole edges, thereby improving the seal
characteristics of the permanent sleeve at the edges of the
holes.
In FIG. 6B, the casing 12 is shown with a defective portion 80, in
which the casing wall is thinner than the rest of the casing. Such
a defect can cause cracks or other openings to form in the casing
wall such that fluid from the formation may leak into the well bore
20. The permanent sleeve also can be used to seal such a defective
section in the casing 12. As shown in FIG. 6B, during the curing
process, the section 84 of the epoxy sleeve 40 extends to conform
to the shape of the casing wall. Although the outer surface of the
epoxy sleeve 40 deforms to conform to the casing wall, the inner
surface 86 of the epoxy sleeve 40 remains substantially
cylindrical. The section 84 of the epoxy sleeve 40 presses the
corresponding section of the elastomer film 82 against the
defective portion 80 of the casing wall to prevent fluid from the
surrounding formation leaking through cracks or other openings in
the casing wall section 80.
The sealing sleeve described above can be used in many
applications. One such application is the isolation of
contaminants, such as water and/or sand, by sealing perforated
sections of the casing. Another application is to completely or
partially seal casing sections through which excessive gas is
flowing from the surrounding formation, which can cause the
pressure in the surrounding perforations to drop prematurely and
adversely affect the producing characteristics of the well.
In another application, the sealing sleeve can be used to isolate
zones in a horizontal well. Producing characteristics along the
horizontal well can change over time. Thus, if a particular section
of the horizontal well is no longer producing, that section can be
isolated using the sealing sleeve to seal off the perforated
openings of the casing in the horizontal well.
Another application of the sealing sleeve is to modify the
injection profiles of a pay zone. For example, referring to FIG. 7,
four wells 102, 104, 106 and 108 are drilled through a pay zone 100
to produce oil. If it is determined that pressure is inadequate for
production purposes, the perforations of some of the wells can be
sealed so that water or air can be pumped into the formation 110
below the pay zone 100 to increase the pressure at the producing
wells. For example, perforations in the wells 102 and 108 adjacent
the pay zone 100 can be sealed using sealing sleeves. Once sealed,
water or air can be pumped down the wells 102 and 108 for injection
at a lower level to increase the formation pressure for wells 104
and 106 and thereby improve production in the wells 104 and
106.
Other embodiments are also within the scope of the following
claims. For example, other types of curing agents which when mixed
with resin will achieve desirable curing temperatures can be used.
A different exothermically reactive source other than thermite can
be used to generate the required heat. Depending upon the
temperatures achieved, the exothermically reactive source or other
energy source may be incorporated as an inner or outer layer of the
inflatable sleeve or as a layer within the substance of the
internal sleeve. The layer in the permanent sleeve can contain a
photosensitive material that is curable with a light source, and
the downhole activatable energy source can produce light of
appropriate curing wavelength, e.g., ultraviolet, instead of heat.
The source of light may be outside of the inflatable sleeve, or the
sleeve may be light-transmissive to enable light produced within
the inflatable sleeve to reach the composite sleeve. Powered by a
battery or a low power connection to the surface, the inflatable
sleeve may comprise a bellows-like thermally-resistant metal
sleeve. The inflatable sleeve may be inflated and deflated by a
pump at the surface. The apparatus and method may be realized using
multiple steps for positioning the composite sleeve, inflatable
sleeve and local heat source.
* * * * *